Note: Descriptions are shown in the official language in which they were submitted.
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ROAD MARKER OR LIGHT BASED WARNING DEVICE
RELATED APPLICATIONS
This application derives priority from New Zealand patent application numbers
595342, 595950
and 596762 incorporated herein by reference.
TECHNICAL FIELD
The application relates to a road marker or light based warning device. More
specifically, the
application relates to a road marker or device with at least one light-
emitting diode that is used to
warn motorists of temperature-related dangerous road conditions such as the
formation of ice.
BACKGROUND ART
Reflective road markers, commonly known as cat's eyes, are used worldwide to
manage traffic
and maintain road safety. These markers generally include reflective material,
visible both
during the day and at night on exposure to light from street lamps or vehicle
headlights. Road
markers are widely used as they are inexpensive to produce, simple to install
and need little or
no maintenance yet still perform a very helpful function for motorists. While
reflective road
markers may be effective in managing traffic, they do not assist motorists in
assessing ambient
temperature and the effect of ambient temperature on driving conditions.
Driving conditions can be hazardous in the presence of ice and, in particular,
black ice. Black
ice is generally known as a thin coating of glazed ice on a road or sidewalk
that is transparent
and, thus, may not be seen. Black ice lacks noticeable ice pellets, snow or
sleet to indicate that
road conditions are dangerous and that driving speed should be reduced.
Bridges and
overpasses may be especially hazardous, as black ice forms first on these
structures due to a
cooling flow of air both above and beneath the structures.
It should be appreciated that it may be useful to have a cat's eye device that
serves the dual
purpose of being a reflective road marker and which alerts drivers to
potential safety hazards
associated with ambient temperature such as ice formation.
One existing technology relating to illuminating road markers powered by solar
cells may be
referred to as a solar road stud as described in US2011135386A1. These markers
or studs
flash constantly to alert drivers to dangerous sections of road or hazardous
conditions. One
drawback of these existing solar road studs is that the flashing lights do not
automatically switch
on and off depending on changes in the conditions. They must also be activated
remotely.
Thus, they are useful solely on sections of road that are always hazardous to
drive and which
are able to be monitored, rather than on sections of road that are
intermittently hazardous
and/or sections that are remote from monitoring sites.
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Other existing technology overcomes the problem of controlling the
illumination of road markers
or signs by linking them to road condition sensors and to a network or data
transmission
system. The network may automatically control warning signals to drivers or
require remote
control. A drawback of those systems is that they are expensive and complex to
install,
operate, maintain and repair and, hence, may be prohibitively costly to
implement. They also
lack flexibility in location as they must be installed proximate an external
data collection point.
One patent publication JP2002-256520 proposes an alternative solution
describing a road
marker that continuously illuminates alternating between colours depending on
the temperature.
Continuous illumination in this manner is not ideal as it means parts wear out
and energy use is
higher than may be needed. In addition, the device described does not
recognise issues
surrounding rapid on-off cycling that can occur thereby resulting in problems
with longevity of
the circuitry and device as a whole.
For the purpose of this specification the term 'comprise' and grammatical
variations thereof shall
have an inclusive meaning - i.e. that it will be taken to mean an inclusion of
not only the listed
components it directly references, but also other non-specified components or
elements.
Further aspects and advantages of the road marker or light based warning
device will become
apparent from the ensuing description that is given by way of example only.
SUMMARY
Described herein is a road marker or device with a thermal sensor that
triggers the
illumination of at least one light-emitting diode at temperatures approximate
to the formation
of ice thereby providing a warning to motorists of hazardous driving
conditions associated
with cold temperatures.
In a first aspect there is provided a road marker comprising a housing
enclosing:
(a) a circuit board;
(b) a thermal sensor coupled to an input terminal on the circuit board wherein
the
thermal sensor has at least 0.5 C of hysteresis to prevent rapid on/off
cycling of the
at least one light-emitting diode;
(c) a photovoltaic (PV) module coupled to an input terminal on the circuit
board;
(d) at least one energy storage element coupled to an input terminal on the
circuit
board;
(e) at least one light-emitting diode coupled to an output terminal of the
circuit board;
wherein the at least one light-emitting diode or diodes illuminate when the
thermal sensor
detects a predetermined temperature.
In a second aspect there is provided a road marker comprising a housing
enclosing:
(a) a circuit board;
(b) a thermal sensor coupled to an input terminal on the circuit board;
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(c) a photovoltaic (PV) module coupled to an input terminal on the circuit
board;
(d) at least one energy storage element coupled to an input terminal on the
circuit
board;
(e) at least one light-emitting diode coupled to an output terminal of the
circuit board
wherein the at least one light-emitting diode or diodes illuminate when the
thermal
sensor detects a predetermined temperature; and
wherein the housing is biased to a position where at least the light emitting
diode or
diodes in the housing sit proud of a surface to which the road marker is
applied and
wherein, when a force is applied against the bias direction, the housing is
depressed into
the surface.
In a third aspect there is provided a road marker comprising a housing
enclosing:
(a) a circuit board linked in parallel with an energy storage device, a
photovoltaic (PV)
module and a thermal sensor all coupled to an input terminal or terminals on
the
circuit board;
(b) at least one light-emitting diode coupled to an output terminal of the
circuit board
wherein the at least one light-emitting diode or diodes illuminate when the
thermal
sensor detects a predetermined temperature; and
wherein the circuit includes a single forward biased diode between the PV
module and the
energy storage device preventing energy leakage from the energy storage device
when light
energy is insufficient to power the PV module.
The above road marker and device may provide a simple and cost-effective
hazard
indicator for mitigating accidents due to unseen road dangers such as ice. The
design is
such that, once installed, the road marker or device requires little
maintenance. Due to the
fact that the design is self-contained, it does not require expensive data
transmission
systems or networks in order to operate reliably. The markers or devices can
also be used
in remote locations as no monitoring is required. Further, the marker or
device is simple in
construction and comparatively inexpensive.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects of the road marker or light based warning device will become
apparent from the
following description that is given by way of example only and with reference
to the
accompanying drawings in which:
Figure 1 illustrates a perspective view of a road marker of one embodiment;
Figure 2 illustrates a top view of a road marker;
Figure 3 illustrates a front view of a road marker;
Figure 4 illustrates a side view of a road marker;
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Figure 5 illustrates an underside view of a road marker;
Figure 6 illustrates an exploded perspective view of a road marker;
Figure 7 illustrates one embodiment of a biased marker;
Figure 8 illustrates an alternative embodiment of a biased marker;
Figure 9 illustrates a beacon embodiment;
Figure 10 illustrates a simple schematic example of a circuit arrangement for
a road marker or
beacon embodiment; and
Figure 11 illustrates a detailed circuit diagram of one embodiment for a
road marker.
DETAILED DESCRIPTION
As noted above, the application broadly relates to a road marker or device
with a thermal
sensor that triggers the illumination of at least one light-emitting diode at
temperatures
approximate to the formation of ice.
For the purposes of this specification, the term 'PV module' refers to a
photovoltaic module
including a plurality of solar cells, also known as a solar cell array.
Photovoltaic modules
generate electrical power by converting solar radiation to direct current (DC)
electricity.
The term 'LED' refers to a light-emitting diode, a semiconductor light source.
LED's operate
over a long lifetime with low energy consumption. LED's are available in a
variety of
colours, any of which may be used for the current application.
The terms 'road marker', 'cat's eye', 'road stud', 'visual signalling unit'
and grammatical
variations thereof may be used interchangeably to describe a reflective device
on a
substrate such as the surface of a road used to alert drivers to changes in
road conditions
associated with cold temperatures.
The term 'black ice' refers to a thin coating of glazed ice on a road or
sidewalk that is
transparent.
The term 'self-contained' refers to the marker not having any external
linkages or protruding
items.
The term 'ambient temperature' refers to the temperature immediately around
the marker
housing.
The term 'illumination' refers to the light emitting diodes being lighted
either continuously or
on an off/on cycle so as to give the effect of flashing or pulsing of light
from the light
emitting diode or diodes.
The term 'about' or 'approximately' and grammatical variations thereof mean a
quantity, level,
degree, value, number, frequency, percentage, dimension, size, amount, weight
or length that
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varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a
reference quantity, level,
degree, value, number, frequency, percentage, dimension, size, amount, weight
or length.
The term 'substantially' or grammatical variations thereof refers to at least
about 50%, for
example 75%, 85%, 95% or 98%.
In a first aspect there is provided a road marker comprising a housing
enclosing:
(a) a circuit board;
(b) a thermal sensor coupled to an input terminal on the circuit board wherein
the
thermal sensor has at least 0.5 C of hysteresis to prevent rapid on/off
cycling of the
at least one light-emitting diode;
(c) a photovoltaic (PV) module coupled to an input terminal on the circuit
board;
(d) at least one energy storage element coupled to an input terminal on the
circuit board
(e) at least one light-emitting diode coupled to an output terminal of the
circuit board;
wherein the at least one light-emitting diode or diodes illuminate when the
thermal sensor
detects a predetermined temperature.
The inventors have found that existing road marker devices exhibit rapid
on/off cycling of the
lights in the event of a temperature on or around the pre-set measurement at
which the light or
lights are activated. Art methods to avoid this include manual switching on or
off or use of a
micro-controller. Manual adjustment is not ideal as it requires labour and
time and the markers
cannot simply be installed and left to operate. Micro-controllers lack the
resilience of passive
componentry as will be described in more detail below plus micro-controllers
carry a higher cost
making the devices less desirable for mass use and production. Avoiding the
need for manual
switching, micro-controllers and yet addressing the issue of rapid cycling via
introduction of a
moderate to high degree of hysteresis in the switch is ideal from a cost and
reliability point of
view.
The thermal sensor may be a bimetallic switch wherein the switch shape and
metal selection are
designed to confer the desired degree of hysteresis. Alternatively, the
thermal sensor may be a
thermocouple or a thermistor again designed to have the desired level of
hysteresis.
Hysteresis is often avoided in switches where an accurate off/on tolerance is
usually favoured.
In the case of the marker and devices described herein, the opposite is true
where a degree of
hysteresis is very important to avoid the circuit turning off and on rapidly
in a cycle. Instead the
circuit should only turn off once a sufficiently warm temperature is reached
where no ice is likely
in road warning applications and only turning on and staying on when ice is a
likelihood. Rapid
on/off cycling may be confusing to the motorist and may result in more rapid
deterioration of the
componentry. The switch ideally turns the circuit on when ice is a risk and
off when ice
formation is no longer a risk. The exact temperature may vary from location to
location.
The thermal sensor may have at least approximately 0.75 C, or 1.0 C, or 1.5 C,
or 2.0 C, or
2.5 C, or 3.0 C, or 3.5 C, or 4.0 C of hysteresis to prevent rapid on/off
cycling of the at least one
light-emitting diode.
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In one embodiment, the degree of hysteresis is biased towards the light-
emitting diode or diodes
remaining illuminated until at least 0.5 C or higher than the set temperature
so as to ensure that
temperature conditions are suitably warmer than the temperature considered
hazardous.
In a second aspect there is provided a road marker comprising a housing
enclosing:
(a) a circuit board;
(b) a thermal sensor coupled to an input terminal on the circuit board;
(c) a photovoltaic (PV) module coupled to an input terminal on the circuit
board;
(d) at least one energy storage element coupled to an input terminal on the
circuit
board;
(e) at least one light-emitting diode coupled to an output terminal of the
circuit board
wherein the at least one light-emitting diode or diodes illuminate when the
thermal
sensor detects a predetermined temperature; and
wherein the housing is biased to a position where at least the light emitting
diode or diodes in
the housing sit proud of a surface to which the road marker is applied and
wherein, when a
force is applied against the bias direction, the housing is depressed into the
surface.
A spring or springs may produce the bias action. Other bias mechanisms may be
used such as
a piston or pneumatic pusher.
The housing may be depressed into the surface when struck by a snowplough or
heavy vehicle.
In one embodiment that marker may include a hemispherical shaped housing made
of a clear
rubber material. This housing may enclose the componentry of the marker and
the marker may
be set into an aperture in the surface such as a road. A casing that mates
with the housing may
be used along with a bias mechanism such as a spring or springs or piston or
pistons. The bias
action of the bias mechanism forces the marker upwards. The casing may have a
lip around
the casing circumference that abuts and retains the housing within the surface
aperture during
normal operation. When a force is applied to the top of the housing, the
housing may be
depressed into the surface aperture against the bias action thereby dropping
the marker within
the surface. By varying the aperture depth and bias travel, the marker may be
set to fully
depress into the surface. When the force is removed, the bias action then
forces the marker
back up to a normal operation or non-depressed position. This mechanism allows
the marker to
depress when a downward force is applied thereby avoiding the marker being
removed by a
snowplough or heavy vehicle.
An alternative biased embodiment may include use of a housing in the shape of
a ball, the ball
shape being retained within a casing inside an aperture in a surface. The ball
housing may be
manufactured from a transparent and resilient material such as rubber. The
marker
components such as LEDs and battery may be retained within the ball. The ball
housing also
may include a counter weight that weights the bottom of the ball so that the
marker tends to
remain in position with the LED lights and a portion of the ball sitting proud
of the surface. The
ball may be biased up relative to the surface by a sprung bearing and the bias
action forces the
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ball against a casing annulus. When a downward force is applied such as that
experienced
from a heavy vehicle or a snowplough, the ball is forced downwards against the
sprung bearing.
The force may also be transferred into rotational motion on the ball that is
free to spin within the
casing. The ball may also include a magnet or magnets (not shown) that are
attracted to a
magnet or magnets on the casing. The magnets may be used to slow or self-
correct rotational
movement of the ball in addition to a counter balance weight.
In a third aspect there is provided a road marker including a housing
enclosing:
(a) a circuit board linked in parallel with an energy storage device, a
photovoltaic (PV)
module and a thermal sensor all coupled to an input terminal or terminals on
the
circuit board;
(b) at least one light-emitting diode coupled to an output terminal of the
circuit board
wherein the at least one light-emitting diode or diodes illuminate when the
thermal
sensor detects a predetermined temperature; and
wherein the circuit includes a single forward biased diode between the PV
module and
the energy storage device preventing energy leakage from the energy storage
device
when light energy is insufficient to power the PV module.
Prevention of battery leakage avoids the battery losing charge when the PV
module receives no
or minimal light energy. A further advantage of the above circuit layout is
that it avoids the need
for voltage controllers or microcontrollers to control electrical flows
thereby avoiding the need for
more expensive and lower reliability components.
The road marker components may all be located within the housing and there are
no external
parts outside the housing. Art methods often utilise external parts such as
external temperature
sensors or wiring linking multiple devices to one controller. The road marker
described herein is
a stand-alone item with no external parts meaning that installation is a
simple process and
maintenance is minimised.
The housing may include a sloped profile relative to the direction of on-
coming or departing
traffic. This slope or the slopes may aid or encourage a depressing force on
the marker into the
surface against the bias direction.
The surface noted in the above aspects may be a road surface but may also be a
post such as a
lamppost; a rail such as a handrail; a crash prevention barrier; or a median
barrier.
The electrical components used in the marker described above may be passive
components.
The components as a whole may be selected to minimise the voltage requirement
to less than 4
volts. The voltage may be minimised to a voltage requirement of less than 3.5
volts, 3 volts, 2.5
volts, 2 volts, 1.5 volts, 1 volt, 0.75 volt, 0.5 volt. An aim of minimising
the voltage requirement is
that the marker can be made from simple components requiring little
maintenance. Low voltage
requirements also serve to extend the battery life of the device when used in
low light situations.
The road marker described above may be temperature resilient sufficient to
withstand the
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temperature of tar seal during road formation. Road markers are generally
fitted while tar seal is
still molten or before settling hence the marker is subjected to extreme
temperatures for at least
a short period of time. Temperature resilience was achieved by use of a metal
enclosure
containing all of the marker contents along with use of passive components and
not using a
micro-controller. Micro-controllers in particular were found by the inventors
to be particularly
sensitive to temperatures experienced during road sealing plus they were also
less resilient in
general and compromised performance over the long term. A high level of
reliability was
identified by the inventors as being critical given that the marker is likely
to be placed in remote
locations. Having to regularly service the markers particularly when in remote
locations would
dramatically compromise the market proposition of the device due to greater
servicing costs.
The ideal device is one that is installed and largely forgotten except when
needed in hazardous
road conditions. The temperature resilience referred to above may be greater
than 100 C. The
temperature may be greater than 150 C. The temperature may be 180 C to 200 C.
The light emitting diode or diodes may flash when the predetermined
temperature is reached
and light energy is received by the PV module independent of the energy level
in the energy
storage device. By use of a parallel circuit arrangement, the energy storage
device becomes
optional allowing the energy storage device to be removed or recharged
independent of light
illumination.
The circuit board may include an LCR circuit sufficient to generate a pulse of
at least 2 volts to
drive a flash from the light emitting diode or diodes. The pulse may be at
least 2.5 volts, at least
3 volts, at least 3.5 volts, at least 4 volts.
The PV module may be activated by energy received from a car light or lights.
While a cat's eye road marker embodiment is generally described, it should be
appreciated that
other road marker devices may also utilise a similar design. The road marker
device may be a
beacon, road marker, flash light or other device utilising the light emitting
components described.
The device may be placed or fixed to a surface or fixed to an intermediate
structure such as a
road cone.
The PV module used in the marker or device may be located on the top surface
of the housing
when mounted to a surface so that it is exposed to light e.g. sunlight. The PV
module may be a
solar panel of greater than 0.1, or 0.2, or 0.5, or 0.75, or 1.0, or 1.25, or
1.5, or 1.75, or 2.0 volts.
The PV module may be a 2-volt solar panel.
When illuminated, the road marker or device described above may produce a
flashing or pulsing
output. The term 'flashing output' may refer to pauses between illuminations
ranging from 0.015
to 5 seconds although pauses may be more or less as desired. The term
'pulsing' may refer to
the amount of light emitted from the light emitting diodes varying in
brightness in a pulsed
manner ranging in cycle length from 0.015 to 5 seconds although pulses may be
more or less as
desired. The marker may produce a flashing output at a frequency of 1-5Hz when
illuminated.
Illumination may be as a single point of light from one LED or multiple lights
from one or more
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LED's. Where multiple LED's are used, they may be arranged so as to form a
shape or word.
In one embodiment, the LED's may be arranged to form the word "ICE".
The flashing output from the marker or device may be produced by the circuit
board that
includes a flasher circuit. The output of this circuit may be an open drain.
Alternatively, the
flashing output may be produced by at least one light-emitting diode
containing an integrated
multivibrator circuit. In a further embodiment, the at least one light-
emitting diode may produce
constant illumination without flashing or pulsing. Alternatively, the circuit
board may be a low
voltage, resistor programmable thermostatic switch wherein the thermostatic
switch may include
at least a temperature-specific resistor, a thermal sensor, a power supply
resistor, a ground
terminal and an output terminal.
The housing of the marker or device when mounted to a surface may define at
least one top
surface and perimeter sides wherein the top surface and perimeter sides
enclose a cavity
accessible at the bottom of the marker. The housing may be formed as a single
piece.
Alternatively, the housing may be formed from a plurality of individual
pieces.
The housing may be formed from an abrasion-resistant material.
The housing may include at least one reflective surface of light-transmitting
material.
At least one surface of the housing may be transparent such that the at least
one light-emitting
diode is visible through the housing.
A removable bottom closure on the marker or device may attach to the housing
to enclose
components within the housing via screws, adhesive or other attachment
methods. A gasket
may be placed between the housing and the removable bottom closure to prevent
ingress of
water or particulates. The gasket may be made of silicone or a similar
deformable material.
The removable bottom closure may be manufactured from cast aluminium.
Alternatively, the
removable bottom enclosure may be constructed from one or more moulded
components. This
bottom closure may house the spring or springs providing a bias force on the
marker. The bias
force may instead be from a piston or spring situated between the housing and
surface.
The bottom closure may be fastened mechanically (e.g. a fastener) or
chemically (e.g. an
adhesive) to a surface. This bottom closure may be adhesively bonded to a
surface such as a
road surface. Alternatively, the bottom closure may be attached mechanically
or chemically to
an item or items proximate to a road such as a handrail or lamppost.
The thermal sensor used in the marker or device may be contained within the
removable bottom
closure. Alternatively, the thermal sensor may be contained within the
housing.
Placement of the thermal sensor may be to enable measurement of the ambient
air temperature
adjacent the road and/or marker. Alternatively, placement of the thermal
sensor may be to
enable measurement of the substrate, e.g. asphalt temperature.
The energy storage element used in the marker or device may be a battery. The
energy storage
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element may be a rechargeable battery that may be trickle charged from a PV
module without
deterioration. The battery may be a nickel cadmium battery or another type of
battery suitable
for use with PV modules.
The circuit board used in the marker or device may be configured to cause the
at least one light-
emitting diode to illuminate when the temperature sensor measures a
temperature (ambient
and/or substrate) approximate when ice may form (the predetermined
temperature). The
illumination temperature may be less than or equal to 5 C. Alternatively, the
illumination
temperature may be less than or equal to 4 C, or 3.0 C, or 2.5 C, or 2.0 C, or
1.5 C, or 1.0 C,
or 0.5 C, or 0.0 C, or -0.5 C, or -1.0 C, or -1.5 C, or -2.0 C.
In the above aspects, the road marker or device may be self-contained. That
is, there may be
no parts or components outside the housing meaning that the marker or device
is easy to
manufacture, sell, ship and install.
As may be appreciated from the above, the road marker or device may provide a
simple and
cost-effective hazard indicator for mitigating accidents due to unseen road
dangers such as ice.
The design is such that, once installed, the road marker or device requires
little maintenance.
Maintenance frequency depends primarily on the life of the energy storage
element, or battery.
Due to the fact that the design is self-contained, it does not require
expensive data transmission
systems or networks in order to operate reliably.
The embodiments described above may also be said broadly to consist in the
parts, elements
and features referred to or indicated in the specification of the application,
individually or
collectively, and any or all combinations of any two or more said parts,
elements or features, and
where specific integers are mentioned herein which have known equivalents in
the art to which
the embodiments relates, such known equivalents are deemed to be incorporated
herein as of
individually set forth,
Where specific integers are mentioned herein which have known equivalents in
the art to which
this invention relates, such known equivalents are deemed to be incorporated
herein as if
individually set forth.
WORKING EXAMPLES
The marker and device are now described with reference to a detailed
description of various
embodiments of the road marker and device.
Figures 1 to 5 illustrate an embodiment of a road marker in an assembled form.
Figure 6 shows
the marker in an exploded perspective view. The road marker, generally
indicated by arrow 1,
is shaped similar to existing cat's eye road markers. The road marker 1
includes a housing 2,
being a metal enclosure with openings to receive a PV module or solar panel 3
affixed to the top
surface of the housing 2 when fitted to a surface (not shown). The road marker
1 includes light-
emitting diodes (LED's) 4. The LED's 4 surrounding area may include one or
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panels 5. The housing 2 may have sloped edges 6 to allow traffic to drive
smoothly over the
marker 1. The marker 1 also includes a base projection or anchor 7 emanating
from the bottom
of the marker 1 used to help anchor the marker 1 in place on a surface. The
anchor 7 may be
inserted into an aperture in the surface. The anchor 7 may include an aperture
13 to hold a
battery (not shown) therein.
The bottom of the marker is shown in Figure 5. The bottom includes a base cast
aluminium
shell component 8 fastened by screws (9) to the housing 2. The base 8 encloses
the internal
components and attaches to the housing 2.
As shown in Figure 6, inside the housing 2 is a moulding 10 that retains the
solar panel 3, the
printed circuit board (PCB) 11, the sensor 12 and the lights 4 (partially).
Figure 7 shows an example of a biased marker 1. The embodiment shown uses a
hemispherical shaped housing 2 made of a clear rubber material. This housing 2
encloses the
componentry of the marker 1. The marker 1 is set into an aperture in the
surface 16 such as a
road 16. A casing 17 that mates with the housing 2 is used along with a bias
mechanism, in this
examples springs or pistons 19. The bias action of the bias mechanism 19
forces the marker 1
upwards. The casing 17 has a lip around the casing circumference that abuts
and retains the
housing 2 within the surface 16 aperture during normal operation. When a force
is applied to
the top of the housing 2, the housing 2 is depressed into the surface 16
aperture against the
bias action 19 thereby dropping the marker 1 within the surface 16. By varying
the aperture
depth and bias travel, the marker 1 can be set to fully depress into the
surface 16. When the
force is removed, the bias action 19 then forces the marker 1 back up to a
normal operation or
non-depressed position. This mechanism allows the marker 1 to depress when a
downward
force is applied thereby avoiding the marker 1 being removed by a snowplough
or heavy
vehicle.
Figure 8 illustrates an alternative biased embodiment where the marker 1
housing 2 is a ball
shape retained within a casing 17 inside an aperture in a surface 16. The ball
housing 2 is
manufactured from a transparent and resilient material such as rubber. The
marker 1
components such as LEDs 18 and battery 15 are retained within the ball 2. The
ball housing 2
also includes a counter weight 21 that weights the bottom of the ball 2 so
that the marker 1
tends to remain in position with the LED lights 18 and a portion of the ball 2
sitting proud of the
surface 16. The ball 2 is biased up relative to the surface 16 by a sprung
bearing 19 and the
bias action forces the ball 2 against a casing annulus 17. When a downward
force is applied
such as that experienced from a heavy vehicle or a snowplough, the ball 2 is
forced downwards
against the sprung bearing 19. The force may also be transferred into
rotational motion on the
ball 2 that is free to spin within the casing 17. The ball 2 may also include
a magnet or magnets
(not shown) that are attracted to a magnet or magnets 20 on the casing 17. The
magnets 20
may be used to slow or self-correct rotational movement of the ball 2 in
addition to a counter
balance weight 21.
Figure 9 shows an alternative device being a beacon 50 utilising many of the
same components
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and principles of the marker 1 described above. The beacon 50 includes a solar
panel (not
shown) linked with an energy source (not shown) and one or more LED lights 53.
The LED
lights 53 are set into a housing 52 that retains the various components of the
assembly. The
housing 52 may be set onto a support or sleeve 51. This sleeve 51 may be
positioned over a
road cone for example (not shown), or made sufficiently large to use as a
warning cone in itself.
Figure 10 shows a simplified schematic of the circuitry 100 inside the marker
1 or device 50.
Figure 11 shows a more detailed circuit diagram of one embodiment of road
marker 1 circuit
100. The circuit 100 may include a solar panel 101 linked in parallel with a
battery 102 and a
circuit board 103. The connection between the solar panel 101 and the battery
102 includes a
one-way diode 104 preventing reverse flow of electricity thus avoiding
draining of the battery
102 in low light energy situations. The circuit 100 also includes a switch 105
being a thermal
sensor switch such as a bimetal switch. The circuit 100 links to one or more
LED lights 106.
Choice of a bimetal switch 105 has been identified as advantageous since the
switch 105
inherently has a degree of hysteresis. Hysteresis is often avoided in switch
where an accurate
off/on tolerance is usually favoured. In the case of the marker 1 and devices
50 described
herein, the opposite is true where a degree of hysteresis is very important to
avoid the circuit
100 turning off and on rapidly in a cycle. Instead the circuit should only
turn off once a
sufficiently warm temperature is reached where no ice is likely in road
warning applications and
only turning on and staying on when ice is a likelihood. Rapid on/off cycling
may be confusing
to the motorist and may result in more rapid deterioration of the componentry.
The switch 105
ideally turns the circuit 100 on when ice is a risk and off when ice formation
is longer a risk. The
exact temperature may vary from location to location but illumination occurs
at around 1-2 C.
In operation, the solar panel 101 generates a 2.2-volt charge to the circuit
board 103. In the
event of no light energy, the battery 102 provides power to the circuit board
103. The battery
102 may have a power output of approximately 1.2 volts. The circuit board 103
shown includes
a flasher circuit so that, when the switch 105 is on, the flasher circuit is
operational and
generates a pulse of light from the LED light 106 or lights 106. The pulse or
flash occurs on a 1-
5 Hz frequency, this frequency varying depending on the level of power
received by the circuit
board 103. The flasher circuit includes an LCR circuit so as to store and
build charge that is
then released in each pulse or flash. The result is that a 4-volt flash can be
generated using
either the 1.2-volt battery 102 power source or the 2.2-volt solar panel 101
power source. The
frequency of flash varies however depending on energy input with a slower
frequency from a
lower voltage input versus a higher rate from a higher voltage input.
Notably, all of the above components are passive electrical components. This
is important to
reduce the energy requirements of the circuit 100 and therefore reduce costs
and maintenance
requirements. Also unexpectedly, the components are remarkably heat stable.
Use of a
microcontroller for example is not possible for at least a road marker 1
application as the
temperature at which tar is used during road manufacture (and the temperature
that the marker
1 is thus subjected to when paid on a road) melts or damages the
nnicrocontroller. In contrast
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the passive components used are remarkably tolerant of the high heat
experienced during road
sealing - up to 190 C. The passive components minimise voltage to less than 4
volts, more
typically less than 2.5 volts.
When the ambient light level exceeds a predetermined level, the PV module
5,101 charges the
rechargeable battery 21, 102. When the ambient light level falls below a
predetermined level,
the rechargeable battery 21, 102 supplies power to the circuit.
Car light may also be used to generate power from the PV module although a
more continuous
energy source such as the sun is preferable.
As shown in at least Figure 2, a light-emitting diode array 106 may be used.
The LED's may be
arranged in various patterns to form shapes or even words such as the word
"ICE".
The road marker 1 or device 50 may be used to warn motorists of temperature
related hazards
by installing at least one road marker 1 or device 50 to a surface e.g. the
road, a handrail or a
lamppost. Typically, multiple markers or devices would be installed in a
target area. At least
one light-emitting diode 7,106 is illuminated in a flashing pattern by the
circuit 100 when the
thermal sensor 20,105 detects a predetermined temperature. In this way,
motorists may be
alerted to the presence of ice such as black ice and potentially other
temperature related road
hazards.
Aspects of the road marker and device have been described by way of example
only and it
should be appreciated that modifications and additions may be made thereto
without departing
from the scope of the claims herein.
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